testing facility, pistole gave us an exclusive look at the type of powerful explosive used in the unsuccessful attack. p.e.t.n., mixed with an another explosive t.a.t.p. to make the underwear bomb. >> when the passengers heard what they thought were fiber crackers, that was the t.a.t.p. initiating, and by the grace of god and good fortune it did not detonate. >> reporter: this is an insidious weapon. >> it is. >> reporter: to test screeners and stay ahead of terrorists, t.s.a. bomb experts like ed kittel create their tone improvised explosive devices, a thermos with explosives in the liner, and the slipper hiding a shoe bomb. >> in this case you push a switch and it's a suicide- activated device. >> reporter: before taking control of t.s.a., pistole spent 26 years at the f.b.i., running major terror investigations. to prevent the next attack, he's pushing intelligence to screeners on the front lines. >> what i want to make sure is that we are not using old information to try to prevent old things from happening, although we need to make sure that another 9/11 doesn't happen. >> reporter: pisto